A New Probe of Line-of-sight Magnetic Field Tangling
Abstract
The Galactic neutral hydrogen (H I ) sky at high Galactic latitudes is suffused with linear structure. Particularly prominent in narrow spectral intervals, these linear H I features are well aligned with the plane-of-sky magnetic field orientation as measured with optical starlight polarization and polarized thermal dust emission. We analyze the coherence of the orientation of these features with respect to line-of-sight velocity, and propose a new metric to quantify this H I coherence. We show that H I coherence is linearly correlated with the polarization fraction of 353 GHz dust emission. H I coherence constitutes a novel method for measuring the degree of magnetic field tangling along the line of sight in the diffuse interstellar medium. We propose applications of this property for H I -based models of the polarized dust emission in diffuse regions, and for studies of frequency decorrelation in the polarized dust foreground to the cosmic microwave background (CMB).
- Publication:
-
The Astrophysical Journal
- Pub Date:
- April 2018
- DOI:
- 10.3847/2041-8213/aabb54
- arXiv:
- arXiv:1802.00011
- Bibcode:
- 2018ApJ...857L..10C
- Keywords:
-
- cosmic background radiation;
- ISM: magnetic fields;
- ISM: structure;
- methods: analytical;
- polarization;
- radio lines: ISM;
- Astrophysics - Astrophysics of Galaxies;
- Astrophysics - Cosmology and Nongalactic Astrophysics
- E-Print:
- Updated to reflect published version